Geophysical surveying (e.g., seismic, electromagnetic) is a technique where two- or three-dimensional “pictures” of the state of an underground formation are taken. Geophysical surveying takes place not only on land, but also in marine environments (e.g., oceans, large lakes). Marine geophysical surveying systems frequently use a plurality of sensor streamers (long cables), which contain one or more sensors to detect energy emitted by one or more sources (e.g. seismic, electromagnetic) and subjected to interaction with underground formations below the water bottom. Electromagnetic streamers may include sensors for sensing electromagnetic fields indicative of hydrocarbon deposits beneath, for example a subterranean deposit beneath the sea floor. Seismic streamers may include sensors for detecting seismic signals reflected from the subterranean formations including the hydrocarbon deposit.
Sensor streamers such as those employed in marine geophysical surveying may be more than 10 kilometers in length. A plurality of such sensor streamers that are spaced apart may be towed in a body of water behind a survey vessel. A survey vessel may tow one or multiple sensor streamers which may comprise electromagnetic streamers alone or may include electromagnetic streamers in combination with seismic streamers.